Black pepper and tarragon essential oils suppress the lipolytic potential and the type II secretion system of P. psychrophila KM02

Abstract

Given the increasing consumer demand for raw, nonprocessed, safe, and long shelf-life fish and seafood products, research concerning the application of natural antimicrobials as alternatives to preservatives is of great interest. The aim of the following paper was to evaluate the effect of essential oils (EOs) from black pepper (BPEO) and tarragon (TEO), and their bioactive compounds: limonene (LIM), β-caryophyllene (CAR), methyl eugenol (ME), and β-phellandrene (PHE) on the lipolytic activity and type II secretion system (T2SS) of Pseudomonas psychrophila KM02 (KM02) fish isolates grown in vitro and in fish model conditions. Spectrophotometric analysis with the p-NPP reagent showed inhibition of lipolysis from 11 to 46%. These results were confirmed by RT-qPCR, as the expression levels of lipA, lipB, and genes encoding T2SS were also considerably decreased. The supplementation of marinade with BPEO and TEO contributed to KM02 growth inhibition during vacuum packaging of salmon fillets relative to control samples. Whole-genome sequencing (WGS) provided insight into the spoilage potential of KM02, proving its importance as a spoilage microorganism whose metabolic activity should be inhibited to maintain the quality and safety of fresh fish in the food market.

Gallic and ferulic acids suppress proteolytic activities and volatile trimethylamine production in the food‐borne spoiler Rahnella aquatilis KM05

“…The Find Prokaryotic Genes tool of the CLC Genomic Module was used to assign protein coding sequences (CDS) to whole‐genome sequences. Next, functional annotation of the CDS was performed using SwissPROT [with Gene Ontology (GO)] and the protein family (Pfam) database 17,18 …”

“…The CLC Genomic Workbench, version 20.0, and CLC Microbial Genomics Module, version 20 plugin (Qiagen) were applied for processing raw sequencing data as in our previous study. 17 The sequence reads from the MiSeq Illumina platform were demultiplexed, and the overlapping paired-end reads were merged. Next, the reads from sequencing platforms were combined and applied for de novo assembly with increasing word size (k = 21, 41, 61).…”

“…Next, functional annotation of the CDS was performed using SwissPROT [with Gene Ontology (GO)] and the protein family (Pfam) database. 17,18 SubMIC determination The subMICs of GA and FA for the KM05 strain were determined by the broth macrodilution method following protocol M07 of the Clinical and Laboratory Standard Institute. 19 Briefly, phenolic acids were diluted in dimethyl sulfoxide (DMSO) (Sigma-Aldrich) to generate solutions at a range of concentrations between 0.1 and 4.0 g L −1 .…”